cp's OEIS Frontend

A229448 Number of 5 X n 0..2 arrays with horizontal differences mod 3 never 1, vertical differences mod 3 never -1, and rows and columns lexicographically nondecreasing.

%I A229448 #12 Jun 05 2022 12:13:26
%S A229448 17,47,128,324,753,1609,3184,5890,10281,17075,27176,41696,61977,89613,
%T A229448 126472,174718,236833,315639,414320,536444,685985,867345,1085376,
%U A229448 1345402,1653241,2015227,2438232,2929688,3497609,4150613,4897944,5749494,6715825
%N A229448 Number of 5 X n 0..2 arrays with horizontal differences mod 3 never 1, vertical differences mod 3 never -1, and rows and columns lexicographically nondecreasing.
%H A229448 R. H. Hardin, <a href="/A229448/b229448.txt">Table of n, a(n) for n = 1..210</a>
%F A229448 Empirical: a(n) = (11/60)*n^5 - (1/2)*n^4 + (15/4)*n^3 - 1*n^2 + (257/30)*n + 6.
%F A229448 Conjectures from _Colin Barker_, Sep 17 2018: (Start)
%F A229448 G.f.: x*(17 - 55*x + 101*x^2 - 79*x^3 + 44*x^4 - 6*x^5) / (1 - x)^6.
%F A229448 a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6) for n>6.
%F A229448 (End)
%e A229448 Some solutions for n=4:
%e A229448 ..0..0..2..2....0..2..2..2....0..0..0..2....0..0..2..2....0..0..2..2
%e A229448 ..0..0..2..2....1..0..2..2....1..1..1..0....1..1..0..0....1..1..0..2
%e A229448 ..1..1..0..0....2..1..0..2....1..1..1..0....1..1..0..0....1..1..1..0
%e A229448 ..2..2..1..1....2..1..1..0....2..2..2..1....1..1..0..0....2..2..2..1
%e A229448 ..2..2..2..2....2..2..1..1....2..2..2..2....1..1..0..0....2..2..2..2
%Y A229448 Row 5 of A229445.
%K A229448 nonn
%O A229448 1,1
%A A229448 _R. H. Hardin_, Sep 23 2013